2-Pyrrolidone-5-carboxylic acid and its sodium salt are generally known for their use as humectants for cosmetics, soaps, lotions including colognes, perfumes, hair preparations, detergent and dentifrices because of their moistening effect and non-irritancy to skin and eye mucosa as disclosed in AJIDEW A-100 and N-50 Spec. sheets, Ajinomoto Co., Inc.